Optimization of Automotive Wheel Lugnut Tightening

An experimental procedure is presented in order to study the simultaneous tightening of automotive wheel lugnuts and to enhance the clamp load uniformity and repeatability. Two different tightening strategies are investigated, namely, the torque-only and the torque-angle control methods. The effect of the tightening speed, initial threshold torque level, and the torque steps is investigated. The study is conducted on two different wheel materials, namely, steel and aluminum. Lugnut tightening is accomplished by using a five-spindle DC fastening system in either a torque-only or torque-angle control mode. The achieved clamp load in each lugnut is monitored by using inserted force washers (load cells). The torque tension data is analyzed and discussed for both steel and aluminum wheels, in order to select the optimum tightening process that achieves the desired uniform clamp load in the wheel lugnuts assembly.